I attempted to log in over a rather shoddy network connection, and I got the "unable to connect to server" popup message. However, before I clicked the "ok" button to retry the attempt, the landing page (with news + multiplayer / campaign buttons) loaded beneath the overlay. I couldn't exit the popup, so I had to click "ok" which terminated the successful connection.
And I just got booted from a campaign map in the same way... popup appears, map loads underneath the overlay:
